Facebook said Monday it is cooperating with the U.S. Secret Service in investigating a poll that recently appeared on the social-networking site asking whether President Barack Obama should be killed.

The popular social networking site said it disabled the poll — apparently another sign of vitriol in the health care debate — as soon as it became aware that it had been posted by an “individual user” using a “third-party developer.” Neither the individual nor the developer were identified by Facebook or the Secret Service, which said it began its investigation Saturday.

“We take any threat against our protectees very seriously, and we will investigate it thoroughly,” Darrin Blackford, a Secret Service spokesman, told Bloomberg News. “We will look at it, take the necessary steps, and work this thing backwards, hopefully to where it originated.”

Facebook spokesman Barry Schnitt said the poll was apparently created over the weekend and Facebook took action when users alerted the company to its existence.

“We got contacted by the Secret Service, who said, ‘Hey, take that down.’ We told them we took it down an hour ago,” Schnitt said.

More than 60,000 developers have created applications for use on the Facebook platform, including many polls.

Schnitt said the developer had previously created a few, mostly “trivial” apps on Facebook.

“We’re working with the U.S. Secret Service, but they’ll need to provide any details of their investigation,” Schnitt said.

Content that appears on Facebook often generates controversy. The Palo Alto-based company’s tolerance of groups that deny the Holocaust, for example, is a source of sharp debate.

TechCrunch founder Mike Arrington has frequently criticized Facebook’s stance on Holocaust deniers. Defenders, including some Jewish Facebook employees, express “a common theme — that the protection of free speech outweighs any damage caused by the existence of this content,” Arrington noted in one post. But, he said, “that’s an argument that both eBay and MySpace have thrown out the window.”

Schnitt said Facebook frequently disables content that violates its taste standards. “There is a lot of gray area,” he added. “We talk to a lot of outside experts, and do a lot of soul searching and try to come up with policy that enables constructive and sometime controversial discussion without infringing on the rights of others. We don’t pretend to have the solutions.”

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